[PATCH] D80409: [MS ABI] Add mangled type for auto template parameter whose argument kind is Integeral

[Reid "Away June-Sep" Kleckner via Phabricator via cfe-commits]

rnk added a comment.

Looks good, but we should test both sides of the MSVC behavior.



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Comment at: clang/test/CodeGenCXX/mangle-ms-auto-templates.cpp:17
+  AutoParmTemplate<0> auto_int;
+  // CHECK: call {{.*}} @"??0?$AutoParmTemplate@$H0A@@@QAE at XZ"
+  AutoParmTemplate<false> auto_bool;
----------------
zequanwu wrote:
> thakis wrote:
> > zequanwu wrote:
> > > thakis wrote:
> > > > Are you sure this is correct? MSVC produces a different mangling (https://godbolt.org/z/VxRfJd) and neither `undname` nor `llvm-undname` / `demumble` can demangle the symbol here (while they demange the msvc output according to godbolt fine).
> > > I use `x64 msvc v19.24` version, which gives `@"??0?$AutoParmTemplate@$MH0A@@@QAE at XZ"`. The extra `M` might come from qualifier mangling. 
> > > 
> > > For `x86 msvc v19.24(WINE)` version, it produces `??0?$AutoParmTemplate@$0A@@@QAE at XZ` for both `AutoParmTemplate<0> auto_int` and `AutoParmTemplate<false> auto_int`. Isn't this a bug?
> > The test at the top says -triple=i386. If you have x64 mangling results in here, you should use a 64-bit triple (ie -tripe=x86_64-pc-windows). If the mangling is structurally different for different bitnesses, we should probably have tests for both.
> > 
> > For symbols that can be exported, we need to match msvc's mangling to be abi-compatible, no matter if we consider the mangling a bug or not.
> In `x64 msvc v19.14`, it still gives the same mangling results as `x86`. >From godbolt, it looks like that the mangled type was only added since `msvc v19.20`. (https://godbolt.org/z/xGT3w-). But the `MSVCMajorVersion` is only up to 1914, which I guess means `v19.14`. 
> 
> I will add a new version for `v19.20` which will add `M[type]` for each auto template parameter.
Please add a second RUN line with a new check prefix to test the behavior both before and after.


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  https://reviews.llvm.org/D80409/new/

https://reviews.llvm.org/D80409